| Restriction fragment length polymorphism (RFLP) markers were used to investigate host plant resistance to four maize pathogens in 117 maize recombinant inbred lines (RILS), derived from the cross of Hi31 (a B68 conversion) and Ki14 (a Thai inbred). The four pathogens are maize mosaic virus (MMV), Erwinia stewartii, Puccinia polysora, and Exserohilum turcicum. The phenotypic data of RILs were analyzed with 127 RFLP loci using MAPMAKER/QTL and single factor analysis of variance.;Ninety-one RILs were evaluated for MMV resistance in a disease nursery in Hawaii in the summer of 1994. Fifty RILs were classified as susceptible and forty-one as resistant. Loci on chromosome 3 near the centromere showed the largest effects, indicating that a major MMV resistance gene was located in this region. This gene, previously named mv, was mapped on chromosome 3, 4 cM and 5.6 cM from RFLP markers umc102 and php20508, respectively.;Seventy-one RILs and ten sub-lines of each parent were planted at Henderson, Kentucky for evaluation and were naturally infected by E. stewartii. Thirty-eight RILs were classified as resistant and thirty-three as susceptible. A major gene conferring resistance to E. stewartii, designated sw1, was mapped on the short arm of chromosome 1, 4 cM and 8.2 cM from RFLP markers umc167 and umc67, respectively.;One hundred and seventeen RILs and twenty sub-lines of each parent were planted at Waimanalo, Hawaii and one hundred and seven RILs were planted at Mindanao, The Philippines to evaluate P. polysora resistance under natural infection. Five QTLs were mapped on chromosomes 2, 4, 6, 9, and 10. The QTL on chromosome 6 appeared to play a particularly important role in conditioning race-nonspecific resistance to P. polysora.;One hundred and ten RILs and ten sub-lines of each parent were evaluated for race-nonspecific resistance to E. turcicum at Mealani, Hawaii in 1993. A clear 1:1 segregation for general resistance characterized RILs in this nursery. Ninety-five RILs were planted in two separate trials to evaluate the response to race 0 and race 1 of E. turcicum, respectively, at Urbana, Illinois in 1994. The QTL located on chromosomal region 3S was important in conferring the race-nonspecific resistance to E. turcicum. |
